MIME-Based Transformations - Mastering phpMyAdmin 2.8 for Effective MySQL Management - page 227

As we can see in the following image, moving the mouse over each choice in the
drop-down menu gives a short explanation of the corresponding transformation.
A more complete explanation of the transformations and the possible options is
available on clicking on the transformation descriptions link.
Transformation Options
We will see in the Examples of Transformations section that some transformations
accept options. For example, a transformation that generates an image will need the
width and height in pixels. A comma is used to separate the values in the option list,
and some options may need to be enclosed within quotes.
Some options have a default value, and we must be careful to respect the
documented order for options. For example, if there are two options and we
only want to specify a value for the second option, we can use empty quotes as a
placeholder for the first option to let the system use its default value.
Requirements for Image Generation
The normal generation of thumbnails requires that some components exist on the
web server and that a parameter in config.inc.php be correctly configured.
The GD2 Library
phpMyAdmin uses internally some functions to create the thumbnails. These
functions need the GD2 library to be present on our PHP server.